Process analysis system

ABSTRACT

A process analysis system for analyzing the efficiency of industrial processes includes a first radio system ( 104 ) associated with an input part of a processing system, and a second radio system ( 105 ) associated with an output part of a processing system, and a Radio Frequency Identification (RFID) tag associated with an item ( 103 ) to be processed, wherein the first and second radio systems are able to communicate with the RFID tag as it and its associated item pass through the processing system, and data associated therewith is stored on a data logging system. The system may be employed to check the time taken to process the item, or to check other parameters of the process, such as sorting accuracy for a sorting process. The system is particularly suited to use in waste product sorting and filtration systems, where RFID tags can be placed on a sample basis on items to be sorted, but may be applied to other suitable processes.

This invention relates to the analysis of the efficiency of industrialprocesses, particularly but not exclusively in the field of wasteproduct sorting.

The task of sorting a quantity of different objects into defined groupsis one that is commonplace in industrial environments. The degree ofdifficulty encountered in the sorting process is very dependent upon thetype of object to be sorted. Regular shaped objects, such as coins forexample, can be sorted into different types relatively easily byexisting machinery, and the efficiency of the process, as measured bythe relative numbers of incorrectly sorted items, can be detected bymeans such as automated observation of the sorted output using camerasand digital image processing systems. Irregularly shaped objects, suchas the contents from household waste bins, are much more difficult tosort in as efficient a manner, as it one cannot guarantee from one binto the next what the contents will be, and in what condition thosecontents are in. Observation of the contents cannot be easily done asthere are so many types of product that may come through the system, andthe products—bottles, cans and cartons etc—may be damaged and deformedaway from any regular shape.

However, sorting machinery has been developed that is able to cope withsuch waste. See for example the products of MSS Inc. 3738 Keystone Av.Nashville, Tenn. 37211 U.S.A, (see also http://www.magsep.com/) whichare industrial waste product sorting machines as typically operated in aMaterial Reclamation Facility (MRF).

MRFs perform the tasks of identifying, separating and recycling varioustypes of waste, whether domestic or industrial. Many processes within aMRF are automated and typically a waste stream comprising mixed wastemay travel along a manual sorting conveyor. This splits the waste streaminto several different streams, each processing one sort of waste. Mixedwaste travelling along the manual sorting conveyor is subject to anumber of analyses to identify the constituents of the waste and,therefore, determine how to sort it.

The efficiency of the sorting process, both in terms of speed ofoperation, and percentage of incorrectly sorted items is importantinformation for the operators of the MRF to know. Data relating to thesefactors can be used to target improvements to the MRF equipment andoperation. Ideally, information on the performance of individualmachines and sub-processes used within the MRF should be obtained.

An existing method of generating efficiency data involves a processengineer examining the contents of the output from a given sortingprocess, counting items that have been mis-sorted and comparing thisagainst correctly sorted items from the same output, so that thepercentage error in the process can be calculated. This is a timeconsuming, messy and dangerous task, and so cannot easily be done veryoften. Changes in efficiency, due to machine malfunction etc, cantherefore be easily missed. Further, the method does not provideinformation on the rate of processing the material.

Rate of processing can be calculated roughly by examining how quickly agiven input of waste product takes to enter the sorting process.However, without reliable information on the quality of the sortingprocess, the information is of limited value.

According to the present invention there is provided a process analysissystem characterised in that it-comprises a first radio systemassociated with an input part of a processing system, and a second radiosystem associated with an output part of the processing system, and aRadio Frequency Identification (RFID) tag associated with an item to beprocessed, and data logging means in communication with the first andsecond radio systems, wherein the first and second radio systems arearranged to communicate with the RFID tag as it passes through theprocessing system and to pass data associated therewith to the datalogging means, so as to record parameters associated with the processingsystem.

Note that the output part of the processing system may be an output ofone part of the processing system, or may be the final output of theprocessing system.

A system according to the present invention provides the advantage thatuseful information is generated relating to the efficacy of theprocessing system without requiring every item that passes through theprocessing system to be associated with a tag. Furthermore, in operationthe analysis system need not be in communication with the processingsystem itself. However, data from the analysis system may be used tocontrol elements of the processing system if, for example, it is foundthat the processing system is deficient in some manner.

RFID tags are conveniently employed as described herein as they can besmall and non-intrusive, and so will have minimal impact on theoperation of the processing system. RFID tags can also be made verycheaply, and so can be regarded as disposable items, eliminating anyneed to recover them once they have passed through the sorting process.Thus, the use of RFID tags is particularly suitable for application tothe study of the sorting of waste products.

The RFID tag is preferably a passive tag. These tags have no internalpower source of their own, and they operate by extracting power from RFenergy impinging upon the tag, and transmit their own signal using thiscaptured energy. This signal transmitted may be, in the simplest case,the RF signal used to energise it, but modified in some fixed manner.For example, the tag may have a detector and radiating antenna whichradiates a signal at double the frequency of the energising signal. Suchtags may be used to identify its presence or otherwise, but has thedisadvantage that individual tags cannot be discriminated from eachother. More advanced tags are able to modulate the received signal in avariable manner, which variations may, for example, comprise of anidentity code. These tags are slightly more expensive than the simplesttags, but are much more versatile, as they can be used to identifythemselves uniquely in the presence of other tags. Preferably the tagused with the current invention is this latter type of tag.

The tag may advantageously be able to store data supplied by theenergising field. These tags are known as read/write tags. This allowsversatility in that data pertaining to the processing conditions extantat a given time may be transferred to the tag. For example, duringpassage through a processing operation, status information relating tothe processing system could be stored on the tag at the input stage andread from it at the output stage. For further information on RFIDtagging systems, see the web site www.rfid.org. Each radio system maycomprise a radio receive channel arranged to receive signals transmittedat a frequency as transmitted by the RFID tag., Each radio system mayfurther incorporate a transmit sub-system able to provide an RFenergising field suitable for energising the RFID tag. Alternatively oras well, a separate transmitter may be used to supply the RF energisingfield. The transmit sub-system or separate transmitter may be adapted towrite information to a suitable RFID tag. Note that the radio systemsmay share some elements of their architecture. In particular, the “backend” processing elements that are used to process the baseband data maybe common to both or all receivers.

The sensitivity of the radio system receivers and RF power transmittedby the tag are preferably chosen such that a signal produced by the tagcan only be received by a single receiver at any one time. Morepreferably these parameters are chosen such that the tag will bedetected by a radio system when the tag is within a known range of thereceive system's antenna. This will, prevent confusion caused by areceiver falsely detecting the presence of a tag, and also give somecertainty about the approximate location of the tagged item.

The analysis system is preferably arranged to record a time eventassociated with the communication with the RFID tag. The time eventrecord may be generated by the radio system and passed to thedatalogger, which may store the event, along with any identity codeassociated with the tag. Alternatively, the datalogger may generate thetime event by recording the time at which it receives a communicationfrom the radio system. In this way, when a tag has passed from an inputof the processing system to an output and read by the first and secondradio systems, the time taken for the tag, and hence the article towhich it is attached, to pass through the process can be calculated.

Where process systems have multiple outputs, such as in a sortingprocess, a radio system is preferably located at each output. A taggedarticle passing through the process can then be tracked to see if itemerges at the correct output.

The data logger is preferably a computer system. The computer system mayobtain data from the radio system via a cable system or via anadditional radio link, or by any other suitable means. The data loggermay be adapted to compute statistics relating to the efficiency of theprocess, for example the speed of processing and percentage ofprocessing errors may readily be computed, and given knowledge of thepercentage of items to be processed to which tags have been attached,the overall quantities of items processed may be estimated.

According to a further aspect of the invention there is provided amethod of analysing a processing system characterised in that itcomprises the steps of:

attaching to an item to be processed a Radio Frequency Identification(RFID) tag;

reading information from the RFID tag using a first radio system as theitem is passed into the processing system;

reading information from the RFID tag using a second radio system as theitem is passed out from the processing system;

passing information relating to the tag from the first and second radiosystems to data logging means.

The invention will now be described in more detail, by way of exampleonly, with reference to the following figures, of which:

FIG. 1 (prior art) shows in block diagrammatic form the requirements ofan MRF sorting facility.

FIG. 2 (prior art) shows in block diagrammatic form the operation of anRFID tagging system.

FIG. 3 shows in block diagrammatic form the current invention beingapplied to a sorting process.

Illustrated in FIG. 1 is a block diagram showing a typical (simplified)process that is undergone when sorting waste products at a facility suchas an MRF. Waste matter arriving at the facility is input to the sortingstation 1. The matter is then separated into basic categories usingknown techniques. A magnetic separator 2 is used to remove ferrousmetals from the waste matter. The ferrous metals are then processedappropriately. Glass products are separated by means of a disc screen 3,and then processed, whereas jets of air 4 are used to filter paper,cardboard and plastics, and to further categorise these once separated.

These sorters and filters are not perfect, and materials can easily endup in the wrong category. Also, items that comprise two or moredifferent materials cannot be correctly sorted into a single materialoutput, and so will need further separation to achieve good results.Thus, errors in sorting are common. Measurement of these errors is thepurpose of the current invention.

FIG. 2 shows a block diagram of the operation of one form of an RFIDtagging system. A tag 5 comprises of a power transducer 6, a modulator 7and an antenna 8. The transducer 6 converts received RF energy into aform that can be used by the modulator 7. On receipt of RF energy from atransmitter 15 within a base station 10, the transducer 6 will power upthe modulator 7, which will transmit a modulated form of the RF energyvia its antenna 8. The energy will be received by a receive module 9 viaantenna system 11 of the base station 10, which will demodulate thesignal and pass data extracted to a control module 12. This will in turnpass the data to a computer system 13 where it may be recorded orfurther processed. Other base stations may be present, and be connectedto the computer system 13 via connections 14.

FIG. 3 shows the application of an RFID system to a processing system asper the current invention. A processor, such as a sorting machine 100 issupplied with material 101 via a conveyor 102. An operator will attachan RFID tag to several items 103 on the conveyor, or alternatively mayintroduce additional items which have had RFID tags already applied tothem, and will record the identity of the RFID tag attached to each itemonto a computer system (not shown). These items then pass into thesorting machine 100 after having their identity codes within the RFIDtags read by a first radio system 104. The first radio system 104 passesthe identity code to the computer system, where it and its time ofarrival are stored.

On output from the sorting system 100 the items will pass either asecond radio system 105 or a third radio system 106. The radio systems105, 106 will read the identity codes of the tagged items 103, and passthis information to the computer system. The computer system againrecords the identity code and time of arrival, and additionally recordswhich radio system 105, 106 received the code from which tag.

The computer system now has all the information required to calculatethe time taken for the items to pass from the input to an output. Givenknowledge of which tag was applied to which item, the computer can alsodetect errors in the sorting process, i.e. which items have beenincorrectly classified by the sorter. With the knowledge of the numberof items that have been tagged and passed through the system, theefficiency of the sorting process can be determined. The proportion oftagged items 103 to untagged items should be chosen such that theresults are statistically significant, bearing in mind the normalthroughput of the sorting machine 100.

In a further embodiment, the first radio system 104 is arranged to writeinformation to the tagged items 103 relating to the process beingmeasured. This information can be read by radio systems 105 or 106 asappropriate, and stored along with identity code information as before.In this way, further information can be annotated to the data suppliedto the computer system which can be used as a check against proceduralerrors being made in the collation of the data.

The skilled person will be aware that other embodiments within the scopeof the invention may be envisaged, and thus the invention should not belimited to the embodiments as herein described.

1. A process analysis system characterised in that it comprises a firstradio system associated with an input part of a processing system, and asecond radio system associated with an output part of the processingsystem, and a Radio Frequency Identification (RFID) tag associated withan item to be processed, and data logging means in communication withthe first and second radio systems, wherein the first and second radiosystems are arranged to communicate with the RFID tag as it passesthrough the processing system and to pass data associated therewith tothe data logging means, so as to record parameters associated with theprocessing system.
 2. A process analysis system as claimed in claim 1wherein the RFID tag is applied to an item to be passed through a wasteproduct sorting facility.
 3. A process analysis system as claimed inclaim 1 wherein the RFID tag does not contain an internal power source,and is arranged, on interrogation from either the first or second radiosystems, to transmit an identity code.
 4. A process analysis system asclaimed in claims 1 wherein the data logging means is arranged to recordinformation relating to the time interval taken for the RFID tag to passfrom the first radio system to the second radio system.
 5. A processanalysis system as claimed in claim 1 wherein a third radio system isassociated with a second output of the processing system, and the datalogging means is arranged to record at which output the RFID tag arrivesafter passing through the processing means.
 6. A process analysis systemas claimed in claim 1 wherein the data logging means comprises acomputer system.
 7. A process analysis system as claimed in claim 1wherein the RFID tag is able to store information written to it using aradio frequency field.
 8. A process analysis system as claimed in claim7 wherein a transmitter is arranged to write data to the RFID tag as itpasses through the processing system.
 9. A process analysis system asclaimed in claim 1 wherein the data logging means is arranged tocalculate statistics pertaining to the processing system based uponparameters provided relating to the quantity and percentage of itemsassociated with a tag and the data measured using the radio systems. 10.A method of analysing a processing system characterised in that itcomprises the steps of: attaching to an item to be processed a RadioFrequency Identification (RFID) tag; reading information from the RFIDtag using a first radio system associated with an input to theprocessing system as the item is passed into the input; readinginformation from the RFID tag using a second radio system associatedwith an output of the processing system as the item is passed from theoutput; passing information relating to the tag from the first andsecond radio systems to data logging means.
 11. A method as claimed inclaim 10 wherein the RFID tag is applied to an item to be passed througha waste product sorting facility.
 12. A method as claimed in claim 10wherein the data logging means records information relating to the timeinterval taken for the RFID tag to pass from the first radio system tothe second radio system.
 13. A method as claimed in claim 10 wherein athird radio system is associated with a second output of the processingsystem, and the data logging means records at which output the RFID tagarrives after passing through the processing means.